Bluetooth Shield a serial port Bluetooth module (Master/Slave) breakout board. You can choose ARDUINO's Digital PIN D0->D7 as Software UART to communicate with Bluetooth Shield(and D0,D1 also is Hardware UART).
Serial port Bluetooth module is fully qualified Bluetooth V2.0+EDR(Enhanced Data Rate) 3Mbps Modulation with complete 2.4GHz radio transceiver and baseband. It uses CSR Bluecore 04-External single chip Bluetooth system with CMOS technology and with AFH(Adaptive Frequency Hopping Feature). Hope it will simplify your overall design/development cycle.
And now, we provide HC-05, which could be setting to Master or Slave by user.
Only between master device and slave device can be paired with each other. Between Master and Master devices or Slave and Slave devices can't be paired each other. The Slave mode could be paired with PDA, PC etc.